Power bank



FIG. 1 is a perspective view of a power bank showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a perspective view of the power bank of FIG. 1 with an electronic device connected thereto.

The broken lines of all the figures are for the purpose of illustrating environment and form no part of the claimed design. 

CLAIM The ornamental design for a power bank, as shown and described. 